Four fire engines and around 25 firefighters were called to a fire at an industrial unit on Oxford Road in Harrow.
Part of a ground floor of a two-storey industrial unit was damaged by fire. The roof of the unit was damaged by smoke. There were no reported injuries.
The Brigade was called at 2027 and the fire was under control by 2117. Fire crews from Harrow, Stanmore and Northolt fire stations attended the scene.
The fire is believed to have been caused by an electrical fault within a paint mixing machine.